Mining machines having oppositely rotating boring heads



July 24, 1956 M. B. KIRKPATRICK MINING MACHINES HAVING OPPOSITELYROTATING BORING HEADS 5 Sheets-Sheet 1 Filed Dec. 21. 1953 Gm o R K a m2 W l mfi mm 4., m O q. QM B m M. 1k. W5. (kl LM NW M M A 0\\1M./0Z..\\\\mh Q \QLG. M Y I WA B O a Q \mC\/. o V H Q) A fi w x w w Q 5 o bw M L m \m MW. .M N l R w I. My

Jilly 24, 1956 M. B. KIRKPATRICK 2,756,037

MINING MACHINES HAVING OPPOSITELY ROTATING BORING HEADS Filed D80. 21.1953 5 Sheets-Sheet 2 v INVENTOR. MAX 3 K/EKPA TE/CK g gm y 1955 M. B.KIRKPATRICK 2,756,037

MINING MACHINES HAVING OPPOSITELY ROTATING BORING HEADS Filed Dec. 21.1953 5 Sheets-Sheet 3 Q I u* INVENTOR.

M u MAX 5. MEKPAfQ/C'K 7' Qb\ BY M gww b WW A rroe/ve v6 III July 24,1956 M. B. KIRKPATRICK MINING MACHINES HAVING OPPOSITELY ROTATING BORINGHEADS 5 Sheets-Sheet 4 Filed Dec. 21. 1953 W E mg 6 mm m K 60 7 B. 5 9 MM M Y B July 24, 1956 M. B. KIRKPATRICK MINING MACHINES HAVINGOPPOSITELY ROTATING BORING HEADS 5 Sheets-Sheet 5 Filed Dec. 21. 1953 K0 mm w V .Wm mm B m A K mm 5 \N M I v M Y w .v \h BM Kw .H. JQW w Q Tl Ll u J Q United States Patent MINING MACHINES HAVING OPPOSITELY ROTATINGBORING HEADS Max B. Kirkpatrick, Anchorage, Territory of AlaskaApplication December 21, 1953, Serial No. 399,255

17 Claims. (Cl. 262-7) In Alaska there are known and proven seams ofcoal of good grade, and of great thickness, regularity, and extent.Except for the coastal cities, of which none are large or populous, itis impractical to import oil as a fuel. For the remainder of theTerritory, and even for the coastal cities, coal would be a near-idealfuel, if it could be made available at a reasonable price from localmines.

The principal obstacle to doing so is the relatively large amount oflabor required in mining the coal under the prevailing conditions,coupled with the high cost of labor in Alaska. As to the conditions,Alaska coal is largely found beneath heavy overburdens, and informations tilted appreciably, say at 30. iv As a conservation measureit is required that mining operations commence at the lowest point in aseam or tract, and proceed thence uphill. This imposes a severe burdenon any mining machine heretofore tried, slows down the operation, andrequires additional labor. The extra labor adds to the cost of providinghousing and maintaining the laborers.

As a result of such economic factors the mining of coal in Alaska hasnot been conducted on a large scale, notwithstanding the tremendousdeposits. Such considerations have given rise to the present invention.With it, the mining under such conditions can be carried out with a veryminimum of labor, the tilt of the coal beds is no deterrent, but is infact converted into a favorable factor, there need be no timbering ofmine shafts and tunnels, the percentage of recovery is as high or higherthan in other known methods other than stripmining (which in Alaska isimpractical because of the heavy overburden, and climaticconsiderations), and the operation can be effected the year round by amachine of comparatively small cost in relation to the value of the coalmined, of great ruggedness and simplicity, and which is capable ofoperating at high efficiency.

In general, the machine of the present invention includes an outershell, which is nonrotative and which advances into a bore as thebreaking away of the working face progresses, this breaking away of theworking face being accomplished in general by the coaction of an outercollar journaled at the forward end (in the direction of advance) of thenonrotative shell, and an inner collar also at the forward end,journaled within and spaced from the outer collar, but rotativedifierentially-usually and preferably in the opposite rotativesense'-together with means for conveying the broken-oflf coal to therear of the machine where it can be conveyed or chuted to a collectingpoint or vehicle, and supplemented-wherever necessary by face cuttersradially disposed between the two collars and rotating as they revolvewith one or the other of such collars, to break away the face materialintervening between the collars. Such a machine may be operated by anoperator stationed within the annular space between the inner and outershells, protected by the outer shell from falling debris, and shieldedagainst dust by proper seals at the journal points, whereby a singleoperator may operateand con- 2,756,037 Patented July 24, 1956 trol themachine, or the operator may, in proper cases, be dispensed with and themachine may be controlled by a remotely-stationed operator. Since thebore is cylindrical, it forms its own roof and floor fillets, andrequires no timbering.

By appropriate changes in size and arrangement, the principles of themachine may be adapted to the obtaining of core samples, and such acoring machine would, of course, be of relatively small size andremotely controlled.

Such a machine may be advanced by traction means which are carried bythe shell and which engage the bore walls, so that the shell may beadvanced positively and with great force, and will advance as readilyuphill as on a level, or downhill. Moreover, it is adapted fortransportation from one bore to a point of beginning of the next bore,by a transport shell, which in effect constitutes an extension of thebore which is about to be commenced.

The machine is so assembled that it can be disassembled with reasonableease, even when at the end of a bore, should there be a need to do so.

It is believed that the objects of the invention and the principleswhich distinguish it may be readily ascertained from the above. Moreparticularly, the invention comprises those features and thosecombinations of struc ture which are shown in the accompanying drawingsin representative forms, and which will be more fully explainedhereinafter and defined in the claims.

Figure l is an axial sectional view of the machine, shown within a boreand in process of removing material .from the working face; certainparts have been broken looking towards its forward end.

Figure 4 is a diagrammatic view, illustrating the manner in which a newbore is started in a typical tilted formation.

Figure 5 is an exploded isometric view of the machine, for comparisonwith Figure 3, showing how certain major subassemblies may bedisassembled.

Figure 6 is a partial forward end view, and Figure 7 is a fragmentaryaxial section through the forward end, showing the addition of facecutters which may be used when required.

Figure 8 is a fragmentary axial sectional view through the machine alongthe line 8-8 of Figure 2, illustrating a torque-resisting keying meansoptionally usable.

Figure 9 is an axial sectional view of a core-sampling machine whichemploys the principles of this invention.

The outer shell 1 is generally cylindrical and can be formed of metalplates, reinforced at points of greatest stress. It is open at bothends. Such a shell is conveniently supported and advanced into a bore Bof approximately the same size by means of traction devices, such as thecrawler tracks 2, distributed angularly about the shell and eachprotruding through a longitudinally disposed slot therein. Each crawlertrack 2 is carried on a driven front roller 20 and a rear roller 21, andis supported as needed by intermediate rollers 22, the whole beingmounted preferably upon the immediate frame 24. This frame 24 issupported by struts 27' from a generally U-shaped trough or frame,indicated at 23, which is itself fixed secured to the shell 1 bysecuring means 26. Preferably, the forward struts 27' intermediate theframe 24 and the fixed frame 23 are adjustable by means such as thescrew devices indicated at 25, so that the crawler track, andparticularly its driven front rollers 20, can be forced hard against thebore within which the shell 1 is entered. At the rear end spring means,indicated at 27, may be interposed between the struts 27' and fixedframe 23, for urging the crawler track 2 outwardly against the bore walland for holding it in contact with the latter.

It is desired to emphasize that the traction means 2 are not steeringmeans, but the direction in which the device is advanced can be alteredgradually by means which will be described later.

At the forward end of the shell 1 is journaled an outer collar 3, whichis of the same or slightly larger diameter than the shell 1. Thrustbearings are indicated at 31 and a retainer ring 39 within the forwardend of the, outer shell 1 but fixed upon the collar 3, or a rearwardextension thereof, retains the collar in place. A seal 32 is preferablyprovided to exclude coal particles and dust from the space within theouter shell 1. The forward edge of the rotative collar 3 is providedwith cutting teeth 33 and 33' or with equivalent devices for cuttingintothe working face,

Coaxially disposed within and fixedly supported from the outer shell 1is an inner shell or duct 4, spaced from the outer shellto provide arather appreciable annular space between the two shells. This duct 4 isprovided with what is in effect an integral forward extension 40, andupon this extension 40, or in effect upon the forward end of the duct 4,is journaled a rotative inner collar 5. This collar, like the outercollar 3, is provided at its forward edge with teeth 50 and 50', orother means to cut into the working face and to break it away.Preferably, the forward end of the inner collar 5 and of the duct 4, orits extension 40,,are all left open for entrance of material, but inaddition the extension 40 inwardly, or to the rear of the inner collar5,is apertured at 49, for entrance of material from the space betweenthe inner and outer collars.

The outer collar 3 is provided with a rearwardly directed generallyconical extension or terminus 34, the rear end of which closely embracesthe rear portion of the duct extension 40,to the rear of the aperture49, and is journaled thereon as indicated at 35 (Figure l), and hereagain a seal 36 serves to prevent or at least minimize entrance of coalparticles or dust into the annular space between the shells 1 and 4. Inaddition, the conical terminus 34 is provided interiorly with liftingvanes 37 which, as the outer collar 3 rotates, will elevate materialbroken off and falling into the space between the collars, and willdeposit that material through the aperture 49 into the interior of theduct 4, or its extension 40.

Interiorly of the inner duct 4 a screw conveyor 6, or the like, may beprovided, carried upon a rotative shaft 60,

so pitched and directed as to convey material deposited withln the duct4, or its extension 40, to the rear of the machine. The shaft 6,together with a forward extension 66, is journaled from the inner duct4, as indicated at 61 and 62, and the shaft is driven by a sprocket gear63, which is keyed to the shaft 69, or to a connecting section 64thereof which joins the shaft 6t) and the forward extension 66 thereof.The sprocket gear 63 extends radially outwardly beyond the inner duct 4,between the latter and its forward extension 40, and these elements 4and 40 are appropriately connected by bridging elements 43,.

which house in the sprocket gear 63.

A large bull gear 38 is carried upon the collar 3 or upon The twocollars are driven from. a motor 9, which may,

be an electric or an air motor, and through gearing 90 to drive asprocket chain 69, and so to drive the sprocket wheel 63 and the innercollar 5, and to drive a pinion 39 l in mesh with the bull gear 38, andso to drive the latter and the outer collar 3. With the arrangementdescribed, the outer collar 3 will be rotated in a given rotativesenseand the innercollar 5 will be rotated in the opposite rota-1 l 4 tivesense. With proper choice of the size of the gears employed, theperipheral speed of each collar or its cutting edge may be madeidentical with that of the other collar, or approximately so, and whenthis is done the two collars will advance into the working face of thecoal seam at approximately the same speed of advance. It is thedifferential rotation of the collars that breaks up the coal betweenthem, but the counterrotation of the collars, which is the preferredtype of differential rotation, cqualizes the torque as between them, andrelieves the traction means 2 of appreciable torque stresses.-

The coal seams in which this mining machine is designed to operate arequite generally uniform in thickness and in direction. However, forgradually changing the direction of advance, whenever that is necessary,there are provided direction-controlling elements such as the wheels 7,journaled in short levers 70, pivotally mounted at 71 at the rear end ofthe outer shell 1, and distributed angularly thereabout. Preferably,there are four such rollers 7, distributed at intervals, and each issecured by such means as the turnbuckle device 72 in a fixed position,but a position which is subject to change. lengthening the lowerturnbuckle element 72 and shortening the upper one, the rear end of theshell 1 may be tilted upwardly and it will then advance in a generally,but only slightly, downward direction. By similarly relatively adjustingthe two lateral rollers 7, the machine may be tilted to advance to oneside or to the other from its general previous direction of advance.

In the large machine, which may be, for instance, eight feet indiameter, an operator may sit upon a seat S within the space between theinner shell 4 and the outer shell 1, in a position where he can controlthe motor 9 for rotating the two collars and where he can also controlthe motors 91, which drive the several traction devices 2. Thus located,the operator is thoroughly protected by the shell 1 against fallingmaterial, and even in r the event of a cave-in behind him he isreasonably well protected, and there are hoses leading, to him forsupply of air and the like, and an electric line for delivery of power.It has been found that the bore, being cylindrical in Shape, requires notimbering, and that the mine roof can be wholly supported, during theentire time that coal is being mined, by the pillar walls intermediateadjoining bores. By successive bores, close together or interconnectingthroughout the height of the seam, a very high percentage of theavailable coal can be removed.

the pillars and the rounding fillets at top and bottom of the bore roofand floor being the only coal not readily recoverable.

It is intended to operate by advancing a tunnel Tor shaft alongthe loweredge of the mine area, large enough to permit the turning of the machinetransversely, even though this tunnel or shaft may have to be timbered.The machine is then transported into this tunnel T within a transportshell A, and at the spot chosen for the start of a new bore B or driftthe machine, reacting fronrthe transport shell, is advanced against theworking face-of coal, and'bores its way into the same, advancing alongthe same angle as the angle of slope of the seam, all as is illustratedin Figure 4. When it has advanced clear of the transport shell A, thelatter may be removed. Thereafter, all coal which is delivered at therear end of the machine by the feed screw 6 may be received upon aconveyor, or within a chute, according to the slope, and

so transported or chuted into the main tunnel, where it.

can be received in mine cars or upon a master conveyor C, and soconveyed out of the mine.

There may be times or locations where the material.

doesnot break otf readily intermediate the teeth33, 33',

and 50, 50, or if it does break off, breaks off in chunks' which-aretoolarge to handle readily. To fit such a situation, face cutters,preferably in the form of radially disposed and generally slightlyconical rollers 8 ands80, are provided. These are best arranged inpairs, angularly For instance, by

disposed about the forward end of the machine, and provided over theirperipheral surfaces with cutters 81. The

roller 8 may be carried on a shaft 83 journaled at 82 in a ring 58 whichis loose and interposed between the inner collar 5 and the extension 40,and the outer end of the shaft 83 is journaled at 84 at the inner sideof the rotative outer collar 3. At the inner end of the shaft 83 isprovided with a gear 85 which meshes with a gear 69 upon the shaftextension 66.

As the outer collar 3 revolves, it of necessity efiects' bodilyrevolution of the roller 8, and since the paired roller 80 is similarlyjournaled but is gear-connected at 86 to the shaft 83, the pairs ofrollers 8 and 80 revolve with the outer collar 3, carrying with them theloose collar 58. At the same time, because of the intermeshing of thegears 85 and 69, the shaft 83 is rotated, and the rollers 8 and 80through their interconnection at 86 are rotated in relatively oppositesenses, preferably toward one another. ers 8 and 80 revolve bodily withthe collar 3 and each individually rotates relatively to the pairedroller while they revolve. Thus revolved and rotated they serve to breakoff the working face of the seam, and to break up any chunks until theyare small enough to handle. The size of the chunks can, in a measure, beregulated by the spacing between the face cutter rollers 8 and 80.

As has been stated, the counterrotation of the inner and outer collarsrelative to one another serves to equalize the torque on the shell 1,but in order to insure against the shells rotation, and to relieve thecrawler tracks 2 of torque-induced stresses in the highest possibledegree, the keying means of Figure 8 may be employed. A key cutter 100is carried by a shaft 101 which is generally radially disposed, butdirected somewhat laterally and downwardly (see Figure 2) to cut intothe fillet portion of the coal seam. The shaft 101 is journaled in theshell 1, and carries gear means, such as the pin gear 102 which mesheswith the bull gear 38, whereby to rotate the cutter 100. An air jet 103,acting within the housing 104, or any equivalent means, serves toelevate the cut-away coal and to deliver it, through a duct 105, intothe inner duct 4.

A key 106, adjustably mounted in a subframe 107 for radial projection orretraction relative to the shell 1, can follow in the keyway K which thecutter 100 cuts, and by its engagement therein serves to absorb most ofthe unbalanced torque stresses. It will be understood that the cutter100 as well as the key 106 may be retractable, and so will not requirepower when conditions permit its non-use.

Alternatively, it may be desired to utilize the principles of the miningmachine described above for core sampling. In such case, as shown inFigure 9, the outer shell and the inner shell are greatly reduced insize and are made more nearly of the same size. the axial shaft is madehollow to receive the core sample, and so is enlarged, say to threeinches in diameter. The inner shell, while reduced in actual diameter,is still larger in relation to the greatly reduced outer shell (whichmay be some eight inches in diameter, for example). The small clearancebetween the inner and outer shells requires some revision of drivearrangements. It will suffice topoint out those features wherein thecoring machine of Figure 9 differs from the larger size mining machinealready described.

The outer shell 1 and the inner shell 4 are provided with theirrespective collars 3' and 5'. In order that these may rotateoppositely'a motor 9' drives the'inner shell 4' by a direct gearconnection at 90', 63, and the gear 90' also drives a countershaft 93,which at 94 carries a pinion that meshes with the bull gear 38'. Thebull gear in turn drives pinions 95, which through clutch means at 96 ofa type which can yield upon encountering excessive resistance (as ahydraulic torque converter), drive the several traction means 2.

The final result is that the face cutter roll- 9 In addition,

The helical screw conveyor 6, as before, is fixed to the shaft 60, butthe latter is now hollow and integral its entire length. At its forwardedge are mounted cutting diamonds 69' or the like, for cutting a corewhich exits through the hollow shaft.

Such a core sampling machine operates by remote control, and the largermining machine may be similarly operated and controlled.

The machine has been shown and described in certain specific forms, notfor purposes of limitation to such specific forms, but by way ofexample. It will be understood that the machine and its severalcomponents may take other forms, and still come within the principles ofthis invention, as defined in the claims. Also, while its use in miningcoal, and under the conditions prevailing in Alaska, has been stressed,obviously it can be used for the mining of any mineral deposits found inseams or thick beds, and anywhere in the world. The references to Alaskacoal mining are not to be taken as limiting, but as indicative of aplace and type of mining for which the machine is eminently suited, andin Which the problems involved gave rise to this invention.

I claim as my invention:

1. A mining machine comprising a generally cylindrical outer shell,traction means carried thereby and protruding therefrom for engagementwith a bore wall to advance the shell axially into such bore, an innerduct axially disposed within and spaced from the outer shell, an outercollar journaled at the forward end of the outer shell and an innercollar journaled at the forward end of the inner duct, each collar atits forward edge being formed for cutting into the bores working face,means to rotate the collars in relatively opposite rotative sensesto-detach material from the working face as the shell is advanced intothe bore, and the inner duct being open at its forward end to receivematerial through the inner collar, and constituting a duct forconveyance thereof to the rear end of the machine.

2. A mining machine comprising a generally cylindrical shell, tractionmeans carried thereby and protruding therefrom at angularly spacedlocations for engagement with a bore wall to advance the shell axiallyinto such bore, an inner duct axially disposed within and spaced fromthe outer shell, an outer collar journaled at the forward end of theouter shell, formed at its forward edge for cutting, and at its rear endformed conically toterminate at the inner duct, a bull gear carriedexternally of said conical terminus, but within the outer shell, arotative shaft located and journaled within said inner duct, a

sprocket gear mounted upon said shaft and extending raby in a givenrotative sense, said inner collar being formed.

at its forward edge for cutting, and drive means Within the spacebetween the inner duct and the outer shell, to

the rear of the collars, and operatively connected to said bull gear andto said sprocket gear to rotate the same, in opposite rotative senses.

3. A mining machine as in claim 2, including a feed screw within saidinner duct and its forward extension,

and connected for rotation with the shaft, to convey materials enteringthe duct to the rear.

4. A mining machine as in claim 2, including generally radially disposedvanes carried interiorly of the outer collars conical terminus, to liftbroken-off material andto deposit the same, through the inner ductsaperture, within the inner duct for delivery at the rear of the machine.

5. A mining machine as in claim 2, including a plurality of angularlydistributed pairs of generally radially disposed and generally conicalface cutter rollers, a loose collar interposed between the inner collarand the inner duet; wherein said rolle'rsare journale'd, heating meansfor saidrollerscarried by and rotative-with the outer collar,-= antlme'ans operatively interen gaging the inner ends of saidrollers with theshaftto rotate the rollers as they're volve with the outer collars, saidrollers being formed ontheirperipheralsurfaces for cutting.

65A mining machine comprising a generally cylindrical shell, an innerduct supported fromand' coaxially of said shell, an outer collarrotatively mounted upon and as a continuation of the shells forward end,and formed for cutting at its forward edge and outwardly thereof suf'ficientlyfoi' working clearance, material collecting and elevating meanscarried by and rotative with-said outer collar, at its-inner end, theinner duct having an aperture adjacent its fo'rward-endlocated toreceive material detachedby the outer collar s cuttingedg'e andcollected and elevated by said-collecting and elevating means, an innercollan also formed for cutting about its forward edge, and rotativelymounted upon-and as a continuation of the forward end of said innerduct, and openthrough for direct admission to the inner duct of materialdetached by and entering through said inner collar, to-join the materialdii ected crawler tracks mounted within but protruding from the outershell to engage the bore wall, and angularlyspaced about the axis of theouter shell to support the latter generally centralized within theclearance space, and means to drive said crawler tracks for advance ofthe shell.

8. Amining machine as in claim 6, including cutting means projectingradially of the outer shell to cut a key way into the bore wall as theshell advances, and a key separate from said cutting means, carried bythe shell and projecting therefrom, andextending longitudinally inposition to engage in said keyway and to resist torque forces tending torotate the shell.

9.'A mining machine as in claim 8, including means operatively connectedto each of the keyway cutter and the key, and operable to retract thesame at will.

10. A mining machine as in claim 7, including means to force the crawlertracks outwardly from the shell into firtn 'engagement with the borewall, regardless of variations in-the clearance.

11'. vA miningmachineas in claim 7, including positive- 1y -acting'meansat the forward end of the crawler tracks to force the latteroutwardly-from the hull by a distance approximating the clearance space,for engagement with the bore wall, and means resiliently urgingoutwardly the rearend of the crawler tracks, the drive for the crawler Ftraeksbeing operatively connected to the front end thereof.

12. A mining machine as in claim 6, including a rearwardly directedconical extension formed upon the outer collar, and joined thereto aboutacircle intermediate its forward cutting edge and its rear rotativemount upon the outeushell, andjournaled about the inner duct to the rearof the latters aperture, to seal off the material collecting 14.4: Aminingmachine-as in claim 6, wherein the collarrotating means isorganizedand arranged, in relation'to the"relativesizesof the/cuttingedgesof the outer and inner collars,-to rotate each such collar and itscutting edgeatsubstantially the same lineal speed.

l5 A'mining machine comprising a generally cylindri-- cal shell capableof advance into a bore being cut, an inner'duct-supported from andcoaxially-of said shell, and apertured to the rear of its forward end,an outer collar rotatively mounted upon and as a continuation of theshells forward end, and formed for cutting at its forward edge, materialcollecting and elevating means carried by and rotative with said outercollar, inwardly of its forward end, to deposit material within saidinner duct,

' throughthe latters aperture, an inner collar journaled upon theforward end of said inner duct, ahead of its aperture, and open to theinner duct for passage of material, the forward edgeof said inner collarbeing also formed for cutting, a screw conveyor within the inner ductfor moving materials rearwardly therein, formed with an axiallydirectedshaft; and drive means for the outer collar with its materialcollecting and elevating means, for the inner collar, and for the screwconveyor, comprising ,a driven Wheel on the screw conveyor shaft, to therear of the inner ducts aperture, the inner duct beingdivided forprotrusion of said driven wheel, bridging elements joiningthe dividedparts of the inner duct and substantially, housing said driven wheel,the screw conveyor shaft extending forwardly and directly connected tothe.inner collar to drive the latter, a drive gear upon said .outercollar, to the rear ofthe material collecting and .elevating ,means, andmeans located intermediate the outer shelll and the inner duct, and'operatively connected to,each.,of..said drive gear and said drivenwheel to rotate themnand their respective collars, in opposite rotativesenses.-

16.. Aminingmachine comprising a generally cylindrical shell, for,advance axially into a here being cut, an outericollervformed forcutting, at its forward edge and rotativelygmounted upon the forward endof .said shell, an inner collar also formed for cutting at its forwardedge and rotatively supported from the shell within said outercollar,drive means operatively connected to said collars -to revolve the samecoincidentally but differentially, radially disposed facecuttersdistributed about the annular;space;between the inner and outer collarsand their cutting; edges,,,and mounted.in oneof the-collarstoqrevolve:therewith,.each face cutter being formed as a body ofrevolution about its general radial axis and with cutting bitsdistributedlengthwise, and means to rotate each face .eutter about itsaXis while it revolves bodily with its mounting ,collar.

17. A .mining;.machine as in claim 16, wherein .the face cutters arearranged in pairs, and their rotating means are arranged. tovrotateuthecuttersof each pair in .rela' tively opposite rotative senses.

References, Cited in the fileof this patent UNITED STATES PATENTS1,043,185 Wittich Nov. 5, 1912 1,326,480 Dana Dec. 30, 1919 1,511,957Freda Oct. 14, 1924 1,639,215 De Grassi Aug. 16, 1927 1,645,007 JohansenOct. 11, 1927 1,653,111 Lobbey Dec. 20, 1927 2,669,441 Castanoli Feb.16, 1954

1. A MINING MACHINE COMPRISING A GENERALLY CYLINDRICAL OUTER SHELL,TRACTION MEAND CARRIER THEREBY AND PROTRUDING THEREFROM FOR ENGAGEMENTWITH A BORE WALL TO ADVANCE THE SHELL AXIALLY INTO SUCH BORE, AN INNERDUCT EXIALLY DISPOSED WITHIN AND SPACED FROM THE OUTER SHELL, AN OUTERCOLLAR JOURNALED AT THE FORWARD END OF THE OUTER SHELL AND AN INNERCOLLAR AT ITS FORWARD EDGE BEING FORMED THE INNER DUCT, EACH COLLAR ATITS FORWARD EDGE BEING FORMED FOR CUTTING INTO THE BORE''S WORKING FACE,MEANS TO ROTATE THE COLLARS IN RELATIVELY OPPOSITE ROTATIVE SENSE TODETACH MATERIAL FROM THE WORKING FACE AS THE SHELL IS ADVANCED INTO THEBORE, AND THE INNER DUCT BEING OPEN AT ITS FORWARD END TO RECEIVEMATERIAL THROUGH THE INNER COLLAR, AND CONSTITUTING A DUCT FORCONVEYANCE THEREOF TO THE REAR END OF THE MACHINE.